UN Special N° 643 Septembre · September 2005

With 2 million visitors the first year and almost 6 million people a year today, the Eiffel Tower is a real crowd pleaser. At the crossroads of the entire world, more than 200 million visitors have come since its construction. The curvature of the uprights is mathematically determined to offer the most efficient wind resistance possible. As Eiffel himself explains: «All the cutting force of the wind passes into the interior of the leading edge uprights. Lines drawn tangential to each upright with the point of each tangent at the same height, will always intersect at a second point, which is exactly the point through which passes the flow resultant from the action of the wind on that part of the tower support situated above the two points in question. Before coming together at the high pinnacle, the uprights appear to burst out of the ground, and in a way to be shaped by the action of the wind».